As before, a little tactful urging is occasionally necessary in order to
secure a response.

SCORING. _Three satisfactory responses out of five_ are necessary for
success. Any real similarity is acceptable, whether fundamental or
superficial, although the giving of fundamental likenesses is especially
symptomatic of good intelligence.

Failures may be classified under four heads: (1) Leaving one of the
words out of consideration; (2) giving a difference instead of a
similarity; (3) giving a similarity that is not real or that is too
bizarre or far-fetched; and (4) inability to respond. Types (1), (3),
and (4) are almost equally numerous, while type (2) is not often
encountered at this level of intelligence.

This test provokes doubtful responses somewhat oftener than the earlier
test of giving similarities. Those giving greatest difficulty are the
indefinite statements like "All are useful," "All are made of the same
material," etc. Fortunately, in most of these cases an additional
question is sufficient to determine whether the subject has in mind a
real similarity. Questions suitable for this purpose are: "Explain what
you mean," "In what respect are they all useful?" "What material do
you mean?" etc. Of course it is only permissible to make use of
supplementary questions of this kind when they are necessary in order to
clarify a response which has already been made.

While the amateur examiner is likely to have more or less trouble in
deciding upon scores, this difficulty rapidly disappears with
experience. The following samples of satisfactory and unsatisfactory
responses will serve as a fairly adequate guide in dealing with doubtful
cases:--

(a) _Snake_, _cow_, _sparrow_

_Satisfactory._ "All are animals" (or creatures, etc.). "All
live on the land." "All have blood" (or flesh, bones, eyes,
skin, etc.). "All move about." "All breathe air." "All are
useful" (_plus_ only if subject can give a use which they have
in common). "All have a little intelligence" (or sense,
instinct, etc.).

_Unsatisfactory._ "All have legs." "All are dangerous." "All
feed on grain" (or grass, etc.). "All are much afraid of man."
"All frighten you." "All are warm-blooded." "All get about the
same way." "All walk on the ground." "All can bite." "All
holler." "All drink water." "A snake crawls, a cow walks, and a
sparrow flies" (or some other difference). "They are not alike."

(b) _Book_, _teacher_, _newspaper_

_Satisfactory._ "All teach." "You learn from all." "All give you
information." "All help you get an education." "All are your
good friends" (_plus_ if subject can explain how). "All are
useful" (_plus_ if subject can explain how).

_Unsatisfactory._ "All tell you the news." "A teacher writes,
and a book and newspaper have writing." "They are not alike."
"All read." "All use the alphabet."

(c) _Wool_, _cotton_, _leather_

_Satisfactory._ "All used for clothing." "We wear them all."
"All grow" (_plus_ if subject can explain). "All have to be sent
to the factory to be made into things." "All are useful" (_plus_
if subject can give a use which all have in common). "All are
valuable" (_plus_ if explained).

_Unsatisfactory._ "All come from plants." "All grow on animals."
"All came off the top of something." "All are things." "They are
pretty." "All spell alike." "All are furry" (or soft, hard,
etc.).

(d) _Knife-blade_, _penny_, _piece of wire_

_Satisfactory_. "All are made from minerals" (or metals). "All
come from mines." "All are hard material."

_Unsatisfactory._ "All are made of steel" (or copper, iron,
etc.). "All are made of the same metal." "All cut." "All bend
easily." "All are used in building a house." "All are
worthless." "All are useful in fixing things." "All have an
end." "They are small." "All weigh the same." "Can get them all
at a hardware store." "You can buy things with all of them."
"You buy them with money." "One is sharp, one is round, and one
is long" (or some other difference).

Such answers as "All are found in a boy's pocket," or "Boys like
them," are not altogether bad, but hardly deserve to be called
satisfactory. "All are useful" is _minus_ unless the subject can
give a use which they have in common, which in this case he is
not likely to do. Bizarre uses are also _minus_; as, "All are
good for a watch fob," "Can use all for paper weights," etc.

(e) _Rose_, _potato_, _tree_

_Satisfactory._ "All are plants." "All grow from the ground."
"All have leaves" (or roots, etc.). "All have to be planted."
"All are parts of nature." "All have colors."

REMARKS. The words of each series lend themselves readily to
classification into a next higher class. This is the best type of
response, but with most of the series it accounts for less than two
thirds of the successes among subjects of 12-year intelligence. The
proportion is less than one third for subjects of 10-year intelligence
and nearly three fourths at the 14-year level. It would be possible and
very desirable to devise and standardize an additional test of this
kind, but requiring the giving of an essential resemblance or
classificatory similarity.

For discussion of the psychological factors involved in the similarities
test, see VII, 5.